Vizard/Jones BBC Cam Specs for the Shootout

[CamKing]

so you are comfortable with .525" lobe lift on that core? maybe the cam wont flex any more, but the pressure angle is going to be severe. I think you guys should stop at .495 lobe lift with the std core, and go .525 when you go with the 55mm core. that makes more sense to me, and people reading the magazine wont be shaking their head in disbelief.

This test is about making the most power possible between 6-8K.
This was one of the first things I asked, because I calculated I could make over 1,000hp with a .485" lobe, and keep it very reliable.

[dbusch]

you also need to add for the 1.8 rocker ratio (vs. 1.5 the chart was written around) not to mention the high compression allows for much longer exhaust duration and earlier exhuast valve opening which is also explained in the book. Earlier exhaust valve opening = wider LSA. As David explained it to me, once the compression crosses the 14.5-15:1 range, they become much more sensitive to having too narrow of an LSA (which is the inverse of a 10.5:1 motor). Also with this engine being under-valved and under-flowed in every aspect they need the exhaust duration to get it to "hang on" at upper rpm as well as possible. I believe that is why the compression ratio is so important to the overall combination.

right on! low compression usually requires a cam with timing events that produce a tight lobe sep, and vice versa for high compression. if you open the exhaust too soon on a low compression engine it will kill the power.

[CamKing]

the two cams are too close together to bother with. they should grind one on 113 to make it a more meaningful test.

That's something to think about.

[Rick360]

Using the DV LCA chart from his book, he should have picked a LCA at 104-105º for this engine. The 565ci engine with only a 2.35" intake valve puts the CID/ValveDiam (30.05) off the chart on the left at 98-99ºLCA with an adjustment of +2º for the valve arrangement and +3.5º for the 15:1 compression ratio.

Hmmm .... wonder why he didn't spec the cam the way his book proclaims is the way to do it based on the results of thousands of dyno tests?

I can't imagine an engine like that wanting a 104-105LCA, but that's what his book would lead you to believe.

Rick

you also need to add for the 1.8 rocker ratio (vs. 1.5 the chart was written around) not to mention the high compression allows for much longer exhaust duration and earlier exhuast valve opening which is also explained in the book. Earlier exhaust valve opening = wider LSA. As David explained it to me, once the compression crosses the 14.5-15:1 range, they become much more sensitive to having too narrow of an LSA (which is the inverse of a 10.5:1 motor). Also with this engine being under-valved and under-flowed in every aspect they need the exhaust duration to get it to "hang on" at upper rpm as well as possible. I believe that is why the compression ratio is so important to the overall combination.

The chart doesn't mention any adjustment for rocker ratio with regards to LCA. In fact there are even specific BBC examples which would use at least 1.7 ratio. There is mention of rocker ratio in the section on required overlap and yes I understand how LCA affects overlap, but selecting LCA according to the DV book is one of the first decisions about a cam.

I calculated and included the amount he suggests to compensate for the 15:1 CR vs the chart standard of 10.5:1.

I am not asking why either of them chose the cam specs they did for the cam test, I am asking why isn't the cam DV picked for this test at least CLOSE to the way he explains in his book? 110.5ºLCA vs 104.5ºLCA ... that is a HUGE difference in LCA. Did I miss something else in the part about choosing LCA?

I'd say grind one like his book says and test it. Then the loyal book buyers can see what they got for their $20.

Rick

[swatson454]

There are also things like Cd at low valve lifts and how quickly the cam gets the valve off its seat that need to be considered. This is one of those situations where a seat at his seminar would come in quite handy.

[900HP]

Using the DV LSA chart from his book, he should have picked a LSA at 104-105º for this engine. The 565ci engine with only a 2.35" intake valve puts the CID/ValveDiam (30.05) off the chart on the left at 98-99ºLSA with an adjustment of +2º for the valve arrangement and +3.5º for the 15:1 compression ratio.

Hmmm .... wonder why he didn't spec the cam the way his book proclaims is the way to do it based on the results of thousands of dyno tests?

I can't imagine an engine like that wanting a 104-105LSA, but that's what his book would lead you to believe.

Rick

you also need to add for the 1.8 rocker ratio (vs. 1.5 the chart was written around) not to mention the high compression allows for much longer exhaust duration and earlier exhuast valve opening which is also explained in the book. Earlier exhaust valve opening = wider LSA. As David explained it to me, once the compression crosses the 14.5-15:1 range, they become much more sensitive to having too narrow of an LSA (which is the inverse of a 10.5:1 motor). Also with this engine being under-valved and under-flowed in every aspect they need the exhaust duration to get it to "hang on" at upper rpm as well as possible. I believe that is why the compression ratio is so important to the overall combination.

The chart doesn't mention any adjustment for rocker ratio with regards to LSA. In fact there are even specific BBC examples which would use at least 1.7 ratio. There is mention of rocker ratio in the section on required overlap and yes I understand how LSA affects overlap, but selecting LSA according to the DV book is one of the first decisions about a cam.

I calculated and included the amount he suggests to compensate for the 15:1 CR vs the chart standard of 10.5:1.

I am not asking why either of them chose the cam specs they did for the cam test, I am asking why isn't the cam DV picked for this test at least CLOSE to the way he explains in his book? 110.5ºLCA vs 104.5ºLCA ... that is a HUGE difference in LSA. Did I miss something else in the part about choosing LSA.

Rick

Yes and no. The book does not specifically state that rocker ratio affects LSA, that came from the seminar. The book does discuss how low-lift flow and "overlap triangle" affect LSA though. On page 121 of "How to buld horsepower" the "overlap triangle" is discussed with 1.5 vs 1.7 rockers and the LSA needs to be widened. The increased rocker ratio will dramatically affect low-lift flow because the acceleration off the seat is so much faster, less time is spent at low-lift so your mid-lift flow becomes your low-lift flow. (These are my words, not D.V.'s). The book does state that as low-lift flow improves, the wider the LSA needs to be. On page 108 of the HTBH book, the author states: " This works well in practice for a 10.5:1 big block Chevy, but valve-to-piston interference can be an issue with bigger cams, and that may dictate a slightly wider LCA yet." The book also assumes an unrestricted intake for the application. The engine build in this thread, however, is drastically intake valve/port restricted for the application. Because of that, duration is also longer than the book predicts and so is the amount of overlap and exhaust duration and Ithink that's why the LSA was widened. I absolutely promise you that if they had put these heads on a 6500-7000 rpm deal with a more normal compression of say 12.5:1 that the LSA would have been in the 106 range.

[Stan Weiss]

Since I do not have any cam information for a Jones cam I used a Crane 286.

Because flow information is only at every .1" you can really see the interpolation at low lifts

Stan

Code: Select all

Bore = 4.6000     Stroke = 4.2500          Rod Length = 6.3850     RPM = 7500
Wrist Pin Offset = 0.0                     Number of - Intake Valves = 1 - Exhaust Valves = 1
Intake Valve Size = 2.35                   Exhaust Valve Size = 1.88
Intake Valve / Bore Ratio = 0.51087        Exhaust Valve / Bore Ratio = 0.408696
Intake Valve Area = 4.337361 sq. in.       Exhaust Valve Area = 2.775911 sq. in.
Intake Valve Stem Size = 0.375             Exhaust Valve Stem Size = 0.375
Intake Valve Stem Area = 0.110447 sq. in.  Exhaust Valve Stem Area = 0.110447 sq. in.
Valve Lift at which the Valve Area and Window / Curtain Area are the SAME SIZE
At that point the velocity will be the same in both areas
Intake Valve Lift = 0.5875 Inches          Exhaust Valve Lift = 0.47 Inches
Intake Centerline = 111.0                  User Selected DC - Discharge Coefficient = 0.5
Bowl CSA (0.9) Intake = 3.4028 sq. in.     Bowl CSA (0.9) Exhaust = 2.1380 sq. in.
Effective Bowl CSA = 0.88574               Effective Bowl CSA = 0.87762
Valve Lift at which the Bowl Area and Window / Curtain Area are the SAME SIZE
At that point the velocity will be the same in both areas
Intake Valve Lift = 0.46091 Inches         Exhaust Valve Lift = 0.36200 Inches


       I  N  T  A  K  E
Rocker Arm Ratio = 1.700         Valve Lash = 0.0350
Cam       Valve   Crank  Time Port  Time Port   Valve      Valve     Piston  Cylinder    User      Valve     L/D
Lift      Lift    Angle  Area cm^2    Area    Velocity Acceleration  Travel   Volume   Supplied  Discharge  Ratio
                                     cm^2/cc      FPS       FPS^2               cc     Air Flow Coefficient
0.00000 -0.03500   -90.0   0.00000   0.00000    0.00000    0.00000  2.48899  677.8433
0.00050 -0.03415   -85.0  -0.18073  -0.00016    0.63750    2.86875  2.30093  626.6293
0.00200 -0.03160   -80.0  -0.16724  -0.00014    1.91250    5.73750  2.10869  574.2737
0.00350 -0.02905   -75.0  -0.15374  -0.00013    1.91250    0.00000  1.91393  521.2337
0.00600 -0.02480   -70.0  -0.13125  -0.00011    3.18750    5.73750  1.71849  468.0077
0.00900 -0.01970   -65.0  -0.10426  -0.00009    3.82500    2.86875  1.52432  415.1277
0.01250 -0.01375   -60.0  -0.07277  -0.00006    4.46250    2.86875  1.33346  363.1501
0.01630 -0.00729   -55.0  -0.03858  -0.00003    4.84500    1.72125  1.14801  312.6451
0.02100  0.00070   -50.0   0.00370   0.00000    5.99250    5.16375  0.97007  264.1861    0.6090    0.8074  0.0003
0.02650  0.01005   -45.0   0.05319   0.00005    7.01250    4.59000  0.80172  218.3387    8.7435    0.8074  0.0043
0.03350  0.02195   -40.0   0.11617   0.00010    8.92500    8.60625  0.64497  175.6493   19.0965    0.8074  0.0093
0.04130  0.03521   -35.0   0.18634   0.00016    9.94500    4.59000  0.50172  136.6359   30.6327    0.8074  0.0150
0.05080  0.05136   -30.0   0.27181   0.00023   12.11250    9.75375  0.37372  101.7777   44.6832    0.8074  0.0219
0.06200  0.07040   -25.0   0.37258   0.00032   14.28000    9.75375  0.26257   71.5072   61.2480    0.8074  0.0300
0.07450  0.09165   -20.0   0.48504   0.00042   15.93750    7.45875  0.16965   46.2027   79.7355    0.8074  0.0390
0.08900  0.11630   -15.0   0.61549   0.00053   18.48750   11.47500  0.09614   26.1823  101.1810    0.8074  0.0495
0.10600  0.14520   -10.0   0.76844   0.00066   21.67500   14.34375  0.04296   11.6983  126.3240    0.8074  0.0618
0.12300  0.17410    -5.0   0.92139   0.00080   21.67500    0.00000  0.01077    2.9339  151.4670    0.8074  0.0741
0.14200  0.20640      .0   1.09233   0.00094   24.22500   11.47500  0.00000    0.0000  179.2480    0.8059  0.0878
0.16230  0.24091     5.0   1.27496   0.00110   25.88250    7.45875  0.01077    2.9339  207.5462    0.7995  0.1025
0.18400  0.27780    10.0   1.47019   0.00127   27.66750    8.03250  0.04296   11.6983  237.7960    0.7944  0.1182
0.20550  0.31435    15.0   1.66363   0.00144   27.41250   -1.14750  0.09614   26.1823  265.7580    0.7846  0.1338
0.22770  0.35209    20.0   1.86336   0.00161   28.30500    4.01625  0.16965   46.2027  291.4212    0.7681  0.1498
0.25050  0.39085    25.0   2.06849   0.00179   29.07000    3.44250  0.26257   71.5072  317.7780    0.7545  0.1663
0.27230  0.42791    30.0   2.26462   0.00196   27.79500   -5.73750  0.37372  101.7777  332.6521    0.7214  0.1821
0.29450  0.46565    35.0   2.46435   0.00213   28.30500    2.29500  0.50172  136.6359  344.3515    0.6863  0.1981
0.31580  0.50186    40.0   2.65598   0.00229   27.15750   -5.16375  0.64497  175.6493  355.2976    0.6570  0.2136
0.33600  0.53620    45.0   2.83772   0.00245   25.75500   -6.31125  0.80172  218.3387  360.7920    0.6244  0.2282
0.35550  0.56935    50.0   3.01316   0.00260   24.86250   -4.01625  0.97007  264.1861  366.0960    0.5967  0.2423
0.37330  0.59961    55.0   3.17330   0.00274   22.69500   -9.75375  1.14801  312.6451  370.9376    0.5741  0.2552
0.39030  0.62851    60.0   3.32625   0.00287   21.67500   -4.59000  1.33346  363.1501  376.4169    0.5558  0.2675
0.40600  0.65520    65.0   3.46750   0.00300   20.01750   -7.45875  1.52432  415.1277  381.4880    0.5403  0.2788
0.41950  0.67815    70.0   3.58896   0.00310   17.21250  -12.62250  1.71849  468.0077  385.8485    0.5280  0.2886
0.43200  0.69940    75.0   3.70142   0.00320   15.93750   -5.73750  1.91393  521.2337  389.8860    0.5173  0.2976
0.44250  0.71725    80.0   3.79589   0.00328   13.38750  -11.47500  2.10869  574.2737  391.7250    0.5068  0.3052
0.45200  0.73340    85.0   3.88136   0.00335   12.11250   -5.73750  2.30093  626.6293  393.3400    0.4977  0.3121
0.45950  0.74615    90.0   3.94883   0.00341    9.56250  -11.47500  2.48899  677.8433  394.6150    0.4908  0.3175
0.46550  0.75635    95.0   4.00281   0.00346    7.65000   -8.60625  2.67134  727.5062  395.6350    0.4854  0.3219
0.47000  0.76400   100.0   4.04330   0.00349    5.73750   -8.60625  2.84669  775.2598  396.4000    0.4815  0.3251
0.47300  0.76910   105.0   4.07029   0.00352    3.82500   -8.60625  3.01391  820.7993  396.9100    0.4789  0.3273
0.47420  0.77114   110.0   4.08109   0.00353    1.53000  -10.32750  3.17207  863.8729  397.1140    0.4779  0.3281
0.47400  0.77080   115.0   4.07929   0.00352   -0.25500   -8.03250  3.32044  904.2798  397.0800    0.4781  0.3280
0.47280  0.76876   120.0   4.06849   0.00352   -1.53000   -5.73750  3.45846  941.8663  396.8760    0.4791  0.3271
0.46950  0.76315   125.0   4.03880   0.00349   -4.20750  -12.04875  3.58571  976.5210  396.3150    0.4819  0.3247
0.46450  0.75465   130.0   3.99382   0.00345   -6.37500   -9.75375  3.70192 1008.1693  395.4650    0.4863  0.3211
0.45800  0.74360   135.0   3.93534   0.00340   -8.28750   -8.60625  3.80693 1036.7669  394.3600    0.4922  0.3164
0.45000  0.73000   140.0   3.86336   0.00334  -10.20000   -8.60625  3.90066 1062.2940  393.0000    0.4996  0.3106
0.44000  0.71300   145.0   3.77339   0.00326  -12.75000  -11.47500  3.98311 1084.7490  391.3000    0.5093  0.3034
0.42900  0.69430   150.0   3.67443   0.00317  -14.02500   -5.73750  4.05433 1104.1435  388.9170    0.5198  0.2954
0.41600  0.67220   155.0   3.55747   0.00307  -16.57500  -11.47500  4.11438 1120.4972  384.7180    0.5311  0.2860
0.40150  0.64755   160.0   3.42701   0.00296  -18.48750   -8.60625  4.16335 1133.8334  380.0345    0.5446  0.2756
0.38560  0.62052   165.0   3.28396   0.00284  -20.27250   -8.03250  4.20132 1144.1761  374.8988    0.5607  0.2641
0.36820  0.59094   170.0   3.12742   0.00270  -22.18500   -8.60625  4.22839 1151.5467  369.5504    0.5803  0.2515
0.35000  0.56000   175.0   2.96368   0.00256  -23.20500   -4.59000  4.24460 1155.9619  364.6000    0.6042  0.2383
0.33150  0.52855   180.0   2.79723   0.00242  -23.58750   -1.72125  4.25000 1157.4324  359.5680    0.6313  0.2249
0.31080  0.49336   185.0   2.61100   0.00226  -26.39250  -12.62250  4.24460 1155.9619  352.9416    0.6639  0.2099
0.28950  0.45715   190.0   2.41936   0.00209  -27.15750   -3.44250  4.22839 1151.5467  341.7165    0.6937  0.1945
0.26800  0.42060   195.0   2.22593   0.00192  -27.41250   -1.14750  4.20132 1144.1761  330.3860    0.7290  0.1790
0.24600  0.38320   200.0   2.02800   0.00175  -28.05000   -2.86875  4.16335 1133.8334  312.5760    0.7570  0.1631
0.22350  0.34495   205.0   1.82557   0.00158  -28.68750   -2.86875  4.11438 1120.4972  286.5660    0.7709  0.1468
0.20130  0.30721   210.0   1.62584   0.00140  -28.30500    1.72125  4.05433 1104.1435  260.9028    0.7881  0.1307
0.18000  0.27100   215.0   1.43421   0.00124  -27.15750    5.16375  3.98311 1084.7490  232.2200    0.7952  0.1153
0.15920  0.23564   220.0   1.24707   0.00108  -26.52000    2.86875  3.90066 1062.2940  203.2248    0.8004  0.1003
0.13970  0.20249   225.0   1.07163   0.00093  -24.86250    7.45875  3.80693 1036.7669  176.0418    0.8068  0.0862
0.12100  0.17070   230.0   0.90339   0.00078  -23.84250    4.59000  3.70192 1008.1693  148.5090    0.8074  0.0726
0.10350  0.14095   235.0   0.74595   0.00064  -22.31250    6.88500  3.58571  976.5210  122.6265    0.8074  0.0600
0.08770  0.11409   240.0   0.60380   0.00052  -20.14500    9.75375  3.45846  941.8663   99.2583    0.8074  0.0485
0.07400  0.09080   245.0   0.48054   0.00042  -17.46750   12.04875  3.32044  904.2798   78.9960    0.8074  0.0386
0.06150  0.06955   250.0   0.36808   0.00032  -15.93750    6.88500  3.17207  863.8729   60.5085    0.8074  0.0296
0.05050  0.05085   255.0   0.26911   0.00023  -14.02500    8.60625  3.01391  820.7993   44.2395    0.8074  0.0216
0.04150  0.03555   260.0   0.18814   0.00016  -11.47500   11.47500  2.84669  775.2598   30.9285    0.8074  0.0151
0.03370  0.02229   265.0   0.11796   0.00010   -9.94500    6.88500  2.67134  727.5062   19.3923    0.8074  0.0095
0.02700  0.01090   270.0   0.05769   0.00005   -8.54250    6.31125  2.48899  677.8433    9.4830    0.8074  0.0046
0.02200  0.00240   275.0   0.01270   0.00001   -6.37500    9.75375  2.30093  626.6293    2.0880    0.8074  0.0010
0.01730 -0.00559   280.0  -0.02958  -0.00003   -5.99250    1.72125  2.10869  574.2737
0.01370 -0.01171   285.0  -0.06197  -0.00005   -4.59000    6.31125  1.91393  521.2337
0.01000 -0.01800   290.0  -0.09526  -0.00008   -4.71750   -0.57375  1.71849  468.0077
0.00730 -0.02259   295.0  -0.11955  -0.00010   -3.44250    5.73750  1.52432  415.1277
0.00300 -0.02990   300.0  -0.15824  -0.00014   -5.48250   -9.18000  1.33346  363.1501
0.00170 -0.03211   305.0  -0.16994  -0.00015   -1.65750   17.21250  1.14801  312.6451
0.00080 -0.03364   310.0  -0.17803  -0.00015   -1.14750    2.29500  0.97007  264.1861
0.00050 -0.03415   315.0  -0.18073  -0.00016   -0.38250    3.44250  0.80172  218.3387
0.00030 -0.03449   320.0  -0.18253  -0.00016   -0.25500    0.57375  0.64497  175.6493
0.00030 -0.03449   325.0  -0.18253  -0.00016    0.00000    1.14750  0.50172  136.6359
0.00000 -0.03500   330.0  -0.18523  -0.00016   -0.38250   -1.72125  0.37372  101.7777
Totals                   142.36360   0.12300

VALVE     Lift    Opens    Closes   Duration
                Deg BTDC  Deg ABDC
         0.00000  50.44 -- 96.50 -- 326.94
         0.05000  30.42 -- 75.28 -- 285.70
         0.10000  18.31 -- 63.02 -- 261.33
         0.20000  .99 -- 45.39 -- 226.38
         0.30000  -13.04 -- 31.00 -- 197.96
         0.40000  -26.23 -- 17.75 -- 171.52
         0.50000  -39.74 -- 4.06 -- 144.31
CAM
         0.05000  30.42 -- 75.28 -- 285.70
         0.10000  11.76 -- 56.11 -- 247.87
         0.20000  -13.72 -- 30.31 -- 196.58
         0.30000  -36.29 -- 7.54 -- 151.24
         0.40000  -63.09 -- -19.53 -- 97.38

[Stan Weiss]

With 1.8:1 ratio

Stan

Code: Select all

       I  N  T  A  K  E
Rocker Arm Ratio = 1.800         Valve Lash = 0.0371
Cam       Valve   Crank  Time Port  Time Port   Valve      Valve     Piston  Cylinder    User      Valve     L/D
Lift      Lift    Angle  Area cm^2    Area    Velocity Acceleration  Travel   Volume   Supplied  Discharge  Ratio
                                     cm^2/cc      FPS       FPS^2               cc     Air Flow Coefficient
0.00000 -0.03706   -90.0   0.00000   0.00000    0.00000    0.00000  2.48899  677.8433
0.00050 -0.03616   -85.0  -0.19137  -0.00017    0.67500    3.03750  2.30093  626.6293
0.00200 -0.03346   -80.0  -0.17708  -0.00015    2.02500    6.07500  2.10869  574.2737
0.00350 -0.03076   -75.0  -0.16279  -0.00014    2.02500    0.00000  1.91393  521.2337
0.00600 -0.02626   -70.0  -0.13898  -0.00012    3.37500    6.07500  1.71849  468.0077
0.00900 -0.02086   -65.0  -0.11040  -0.00010    4.05000    3.03750  1.52432  415.1277
0.01250 -0.01456   -60.0  -0.07706  -0.00007    4.72500    3.03750  1.33346  363.1501
0.01630 -0.00772   -55.0  -0.04086  -0.00004    5.13000    1.82250  1.14801  312.6451
0.02100  0.00074   -50.0   0.00392   0.00000    6.34500    5.46750  0.97007  264.1861    0.6438    0.8074  0.0003
0.02650  0.01064   -45.0   0.05631   0.00005    7.42500    4.86000  0.80172  218.3387    9.2568    0.8074  0.0045
0.03350  0.02324   -40.0   0.12299   0.00011    9.45000    9.11250  0.64497  175.6493   20.2188    0.8074  0.0099
0.04130  0.03728   -35.0   0.19730   0.00017   10.53000    4.86000  0.50172  136.6359   32.4336    0.8074  0.0159
0.05080  0.05438   -30.0   0.28779   0.00025   12.82500   10.32750  0.37372  101.7777   47.3106    0.8074  0.0231
0.06200  0.07454   -25.0   0.39449   0.00034   15.12000   10.32750  0.26257   71.5072   64.8498    0.8074  0.0317
0.07450  0.09704   -20.0   0.51356   0.00044   16.87500    7.89750  0.16965   46.2027   84.4248    0.8074  0.0413
0.08900  0.12314   -15.0   0.65169   0.00056   19.57500   12.15000  0.09614   26.1823  107.1318    0.8074  0.0524
0.10600  0.15374   -10.0   0.81363   0.00070   22.95000   15.18750  0.04296   11.6983  133.7538    0.8074  0.0654
0.12300  0.18434    -5.0   0.97558   0.00084   22.95000    0.00000  0.01077    2.9339  160.3758    0.8074  0.0784
0.14200  0.21854      .0   1.15657   0.00100   25.65000   12.15000  0.00000    0.0000  189.2028    0.8034  0.0930
0.16230  0.25508     5.0   1.34995   0.00117   27.40500    7.89750  0.01077    2.9339  219.1656    0.7974  0.1085
0.18400  0.29414    10.0   1.55667   0.00134   29.29500    8.50500  0.04296   11.6983  251.1948    0.7925  0.1252
0.20550  0.33284    15.0   1.76148   0.00152   29.02500   -1.21500  0.09614   26.1823  278.3312    0.7760  0.1416
0.22770  0.37280    20.0   1.97296   0.00170   29.97000    4.25250  0.16965   46.2027  305.5040    0.7605  0.1586
0.25050  0.41384    25.0   2.19016   0.00189   30.78000    3.64500  0.26257   71.5072  328.2904    0.7362  0.1761
0.27230  0.45308    30.0   2.39783   0.00207   29.43000   -6.07500  0.37372  101.7777  340.4548    0.6973  0.1928
0.29450  0.49304    35.0   2.60930   0.00225   29.97000    2.43000  0.50172  136.6359  352.8424    0.6641  0.2098
0.31580  0.53138    40.0   2.81221   0.00243   28.75500   -5.46750  0.64497  175.6493  360.0208    0.6288  0.2261
0.33600  0.56774    45.0   3.00464   0.00260   27.27000   -6.68250  0.80172  218.3387  365.8384    0.5980  0.2416
0.35550  0.60284    50.0   3.19040   0.00276   26.32500   -4.25250  0.97007  264.1861  371.5396    0.5720  0.2565
0.37330  0.63488    55.0   3.35996   0.00290   24.03000  -10.32750  1.14801  312.6451  377.6272    0.5520  0.2702
0.39030  0.66548    60.0   3.52191   0.00304   22.95000   -4.86000  1.33346  363.1501  383.4412    0.5347  0.2832
0.40600  0.69374    65.0   3.67147   0.00317   21.19500   -7.89750  1.52432  415.1277  388.8106    0.5201  0.2952
0.41950  0.71804    70.0   3.80007   0.00328   18.22500  -13.36500  1.71849  468.0077  391.8040    0.5064  0.3055
0.43200  0.74054    75.0   3.91914   0.00339   16.87500   -6.07500  1.91393  521.2337  394.0540    0.4938  0.3151
0.44250  0.75944    80.0   4.01917   0.00347   14.17500  -12.15000  2.10869  574.2737  395.9440    0.4838  0.3232
0.45200  0.77654    85.0   4.10967   0.00355   12.82500   -6.07500  2.30093  626.6293  397.6540    0.4752  0.3304
0.45950  0.79004    90.0   4.18111   0.00361   10.12500  -12.15000  2.48899  677.8433  399.0040    0.4687  0.3362
0.46550  0.80084    95.0   4.23827   0.00366    8.10000   -9.11250  2.67134  727.5062  400.0756    0.4636  0.3408
0.47000  0.80894   100.0   4.28114   0.00370    6.07500   -9.11250  2.84669  775.2598  400.8046    0.4598  0.3442
0.47300  0.81434   105.0   4.30971   0.00372    4.05000   -9.11250  3.01391  820.7993  401.2906    0.4573  0.3465
0.47420  0.81650   110.0   4.32115   0.00373    1.62000  -10.93500  3.17207  863.8729  401.4850    0.4563  0.3474
0.47400  0.81614   115.0   4.31924   0.00373   -0.27000   -8.50500  3.32044  904.2798  401.4526    0.4565  0.3473
0.47280  0.81398   120.0   4.30781   0.00372   -1.62000   -6.07500  3.45846  941.8663  401.2582    0.4575  0.3464
0.46950  0.80804   125.0   4.27637   0.00369   -4.45500  -12.75750  3.58571  976.5210  400.7236    0.4602  0.3438
0.46450  0.79904   130.0   4.22874   0.00365   -6.75000  -10.32750  3.70192 1008.1693  399.9040    0.4645  0.3400
0.45800  0.78734   135.0   4.16682   0.00360   -8.77500   -9.11250  3.80693 1036.7669  398.7340    0.4700  0.3350
0.45000  0.77294   140.0   4.09061   0.00353  -10.80000   -9.11250  3.90066 1062.2940  397.2940    0.4770  0.3289
0.44000  0.75494   145.0   3.99535   0.00345  -13.50000  -12.15000  3.98311 1084.7490  395.4940    0.4862  0.3213
0.42900  0.73514   150.0   3.89057   0.00336  -14.85000   -6.07500  4.05433 1104.1435  393.5140    0.4968  0.3128
0.41600  0.71174   155.0   3.76673   0.00325  -17.55000  -12.15000  4.11438 1120.4972  391.1740    0.5100  0.3029
0.40150  0.68564   160.0   3.62860   0.00314  -19.57500   -9.11250  4.16335 1133.8334  387.2716    0.5242  0.2918
0.38560  0.65702   165.0   3.47713   0.00300  -21.46500   -8.50500  4.20132 1144.1761  381.8338    0.5393  0.2796
0.36820  0.62570   170.0   3.31138   0.00286  -23.49000   -9.11250  4.22839 1151.5467  375.8830    0.5575  0.2663
0.35000  0.59294   175.0   3.13800   0.00271  -24.57000   -4.86000  4.24460 1155.9619  369.8704    0.5789  0.2523
0.33150  0.55964   180.0   2.96177   0.00256  -24.97500   -1.82250  4.25000 1157.4324  364.5424    0.6045  0.2381
0.31080  0.52238   185.0   2.76458   0.00239  -27.94500  -13.36500  4.24460 1155.9619  358.5808    0.6370  0.2223
0.28950  0.48404   190.0   2.56167   0.00221  -28.75500   -3.64500  4.22839 1151.5467  350.0524    0.6711  0.2060
0.26800  0.44534   195.0   2.35686   0.00204  -29.02500   -1.21500  4.20132 1144.1761  338.0554    0.7045  0.1895
0.24600  0.40574   200.0   2.14729   0.00186  -29.70000   -3.03750  4.16335 1133.8334  325.7794    0.7451  0.1727
0.22350  0.36524   205.0   1.93295   0.00167  -30.37500   -3.03750  4.11438 1120.4972  300.3632    0.7632  0.1554
0.20130  0.32528   210.0   1.72147   0.00149  -29.97000    1.82250  4.05433 1104.1435  273.1904    0.7794  0.1384
0.18000  0.28694   215.0   1.51857   0.00131  -28.75500    5.46750  3.98311 1084.7490  245.2908    0.7933  0.1221
0.15920  0.24950   220.0   1.32042   0.00114  -28.08000    3.03750  3.90066 1062.2940  214.5900    0.7982  0.1062
0.13970  0.21440   225.0   1.13466   0.00098  -26.32500    7.89750  3.80693 1036.7669  185.8080    0.8043  0.0912
0.12100  0.18074   230.0   0.95653   0.00083  -25.24500    4.86000  3.70192 1008.1693  157.2438    0.8074  0.0769
0.10350  0.14924   235.0   0.78982   0.00068  -23.62500    7.29000  3.58571  976.5210  129.8388    0.8074  0.0635
0.08770  0.12080   240.0   0.63931   0.00055  -21.33000   10.32750  3.45846  941.8663  105.0960    0.8074  0.0514
0.07400  0.09614   245.0   0.50880   0.00044  -18.49500   12.75750  3.32044  904.2798   83.6418    0.8074  0.0409
0.06150  0.07364   250.0   0.38972   0.00034  -16.87500    7.29000  3.17207  863.8729   64.0668    0.8074  0.0313
0.05050  0.05384   255.0   0.28494   0.00025  -14.85000    9.11250  3.01391  820.7993   46.8408    0.8074  0.0229
0.04150  0.03764   260.0   0.19920   0.00017  -12.15000   12.15000  2.84669  775.2598   32.7468    0.8074  0.0160
0.03370  0.02360   265.0   0.12490   0.00011  -10.53000    7.29000  2.67134  727.5062   20.5320    0.8074  0.0100
0.02700  0.01154   270.0   0.06107   0.00005   -9.04500    6.68250  2.48899  677.8433   10.0398    0.8074  0.0049
0.02200  0.00254   275.0   0.01344   0.00001   -6.75000   10.32750  2.30093  626.6293    2.2098    0.8074  0.0011
0.01730 -0.00592   280.0  -0.03133  -0.00003   -6.34500    1.82250  2.10869  574.2737
0.01370 -0.01240   285.0  -0.06562  -0.00006   -4.86000    6.68250  1.91393  521.2337
0.01000 -0.01906   290.0  -0.10087  -0.00009   -4.99500   -0.60750  1.71849  468.0077
0.00730 -0.02392   295.0  -0.12659  -0.00011   -3.64500    6.07500  1.52432  415.1277
0.00300 -0.03166   300.0  -0.16755  -0.00014   -5.80500   -9.72000  1.33346  363.1501
0.00170 -0.03400   305.0  -0.17994  -0.00016   -1.75500   18.22500  1.14801  312.6451
0.00080 -0.03562   310.0  -0.18851  -0.00016   -1.21500    2.43000  0.97007  264.1861
0.00050 -0.03616   315.0  -0.19137  -0.00017   -0.40500    3.64500  0.80172  218.3387
0.00030 -0.03652   320.0  -0.19327  -0.00017   -0.27000    0.60750  0.64497  175.6493
0.00030 -0.03652   325.0  -0.19327  -0.00017    0.00000    1.21500  0.50172  136.6359
0.00000 -0.03706   330.0  -0.19613  -0.00017   -0.40500   -1.82250  0.37372  101.7777
Totals                   150.73752   0.13023

VALVE     Lift    Opens    Closes   Duration
                Deg BTDC  Deg ABDC
         0.00000  50.44 -- 96.50 -- 326.94
         0.05000  31.28 -- 76.19 -- 287.47
         0.10000  19.43 -- 64.22 -- 263.65
         0.20000  2.71 -- 47.14 -- 229.85
         0.30000  -10.76 -- 33.30 -- 202.54
         0.40000  -23.31 -- 20.71 -- 177.39
         0.50000  -35.91 -- 7.92 -- 152.01
CAM
         0.05000  30.42 -- 75.28 -- 285.70
         0.10000  11.76 -- 56.11 -- 247.87
         0.20000  -13.72 -- 30.31 -- 196.58
         0.30000  -36.29 -- 7.54 -- 151.24
         0.40000  -63.09 -- -19.53 -- 97.38

[rookie]

There are also things like Cd at low valve lifts and how quickly the cam gets the valve off its seat that need to be considered. This is one of those situations where a seat at his seminar would come in quite handy.

This is true, as well as what 900HP said, if the reader applies all of the info taught they will have a better picture, but all applications can’t be covered in one article or one book that is what I think his BBC part two addresses is the more extreme output motors.

Like the fact that, not only is rocker ratio one thing to take in to account but also what that rocker actually returns.
Intake valve size is important but also how well the head flows down low greatly affects LCA, if you compare this 717 HP 10.1 street 509 with 1.7 ratio rockers 2.25 valve and lazy low lift flow you see where the need of a 105 LCA is needed.

Quote from article; Our friend and frequent PHR contributor David Vizard spec'd the cam with a tight lobe separation angle of 105 degrees.
Read more: http://www.popularhotrodding.com/tech/0 ... z1bSmLTM9r

[900HP]

I asked DV about the cam and lobe seperation selection and he said that it was based on cylinder head flow of the heads being used. He says in the book that this is the best way to do it but because the average hot-rodder does not have access to a flow-bench the chart has been modified basing flow off of intake valve diameter vs. bore area. He stated that if you had an extremely efficient valve/port arrangement that it would require a wider lobe seperation than an inefficient one. He also stated that exhaust efficiency and header tuning can have an impact on lobe separation as well. This is all in the How to build Horsepower book. He went on to say that the engine does not know if it has a 2.0" valve that flows 400 cfm or if it has a 3.0" valve that flows only 300 cfm. All the engine knows is flow. Now we are getting into the low-lift flow argument and a whole other can of worms. The engine only sees airflow, getting the airflow at the correct time and using the airflow the most efficient way possible is the big trick here.

Call any camshaft manufacturer other than Mike Jones (I put that in there so I didn't get scolded ) and they will give you a different camshaft recommendation every time you call. Call a different company and get just as many more recommendations that aren't based off of anything more than experience and trying to guess what catalog cam will fit the motor best. If you use David's chart, it will predict a camshaft that is much closer than just ordering a "recommended" cam almost every time, unless you get very lucky.

One other point he made. At lower compression it is best to "err" to the tighter side of things with LSA because it doesn't hurt power as much as being too wide. As compression goes up, this situation reverses and it is best to "err" to the slightly wider side of things as being too tight may hurt power more than being slightly too wide.

[900HP]

He also says: The chart in the book uses valve size only to calculate seat velocity, when D.V. uses "cam master" it uses actual flow. The assumption in the book is that you have a valve and seat arrangement that has a standard flow like an off the shelf head you would normally get from a catalog. The Dart heads in this build have an older 45* seat from a "cup car" which was highly sucessful and popular back in the early '90's. These heads have approximately 7-10% more flow in the range during overlap and therefore the valve appears to be much bigger to the engine and hence the wider seperation.

[Stan Weiss]

The Green (Intake) and Red (Exhaust) lines are the Vizard head.

The Blue (Intake) and Cyan (Exhaust) lines are a ported DART Big Chief 14 Deg with 2.45 Inatake valve and flows over 535 cfm with 55 deg Intake and Exhasut seats.

Stan

[F1Fever]

He also says: The chart in the book uses valve size only to calculate seat velocity, when D.V. uses "cam master" it uses actual flow. The assumption in the book is that you have a valve and seat arrangement that has a standard flow like an off the shelf head you would normally get from a catalog. The Dart heads in this build have an older 45* seat from a "cup car" which was highly sucessful and popular back in the early '90's. These heads have approximately 7-10% more flow in the range during overlap and therefore the valve appears to be much bigger to the engine and hence the wider seperation.

when I wrote my cam calculator I tried to take Vizards chart and "math it out" so I could write the program. It called for a tight LSA of 107*... now if I read the chart correctly that is what it should have run. And as most here noted, including Jones, Vizard went way wider than expected.

Three things could be wrong here (or a combination of any),
1: I did not correctly read that chart (I doubt this),
2: the calculator selects the cam that will best match the head / ci rpm range and because they were going for more RPM than the heads called for with that ci he went with a wider LSA to bolster an extended RPM range.
3: as noted, the Vizards cam program uses flow instead of valve size to calculate LSA

now if it's number 3 primarily why push the valve size to select LSA b/c most anybody using this formula probably has a pretty good idea what their heads flow.

I would like to ask both Jones and esp Vizard if this was going to peak at 7k and not worry about carrying the RPM to 8500 what size cam (and mostly LSA) would have been selected?

[rookie]

The Cam Master program takes in to account,
Application from towing to pro race in 6 stages
Type of cam; hyd, solid, flat tappet or roller
Type of port from stock to pro ported
Test pressure of head flow ie; 28”
Valve size, intake and exhaust
Flow from .025 .050 .100 .150 and so on
Bore / stroke, compression, rod length, rocker ratio, water temp, fuel octane
Max rpm / Required rpm
NOS jet size and how many (plate 1 jet or fogger 8 jets) or Boost for those applications.

[rookie]

Another thing to take in to account on LCA is what is the lowest rpm the engine has to operate at as David addresses in the overlap section of his max performance sbc book.
If you look at this engines rpm range (link below) it is all done by the time the Vizard – Jones engine is just getting started, in a street engine as in the link below it is as much or more about usable power/rpm as it is max usable rpm.
http://www.popularhotrodding.com/tech/0 ... z1bSmLTM9r